1. Field of the Invention
This invention relates to a controlling device for an engine and a controlling device for a non-stage transmission for a vehicle, and more particularly to a controlling device for a non-stage transmission for a vehicle by which the transmission gear ratio control is enabled appropriately in response to a running condition of the vehicle.
This invention further relates to a controlling device for a non-stage transmission for a vehicle by which the vehicle will not suffer from hunting when it runs on an uneven road surface (e.g., a rough road).
This invention relates to an engine controlling device which has a fail-safe function for a fixed transmission gear ratio running condition of a motorcycle, an automobile or the like, which includes a non-stage transmission.
This invention also relates to a vehicle controlling device for a motorcycle, an automobile, or the like, which includes an automatic fixed velocity running means, a non-stage transmission, and a non-stage transmission controlling means.
2. Description of the Prior Art
A non-stage transmission which is carried on an automobile, motor-bicycle, a motorcycle, or the like (hereafter referred to only as a "vehicle") changes the speed of a power of an internal combustion engine at a predetermined transmission gear ratio (ratio) to enable an efficient running of the internal combustion engine, by which it is enabled to attain improvements in fuel cost. Control of such a non-stage transmission for a vehicle is executed commonly such that the actual transmission gear ratio may coincide with a target transmission gear ratio which is calculated from a throttle opening, an engine speed or the like. Such a controlling device for a non-stage transmission for a vehicle is disclosed, for example, in Japanese Patent Laid-Open No. 62-273189. The controlling device controls a non-stage transmission in response to velocity information of the vehicle and throttle opening information.
The prior art described above has the several problems. In particular, the conventional controlling device for a non-stage transmission for a vehicle as disclosed in Japanese Patent Laid-Open No. 62-273189 relies upon the detection of current velocity information of the vehicle and current throttle opening information, in other words, a current running condition of the vehicle, and executes control of the non-stage transmission in response to a result of a current running condition. Accordingly, the control response of the non-stage transmission is low.
In the vehicle on which the non-stage transmission is carried, fuel injection to the engine is controlled in response to throttle opening information, engine speed information and so on, and the velocity of the vehicle is controlled thereby. Since control of the non-stage transmission is then executed using vehicle velocity information and so on, some delay in response takes place in control of the non-stage transmission, and a comparatively long period of time is required until the vehicle is brought into a running condition that is intended by the driver, which leads to deterioration in running performance.
Accordingly, when it is intended to suddenly open the throttle valve to achieve rapid acceleration, or when the vehicle is running in high altitudes or the like and the atmospheric pressure is different from that at a lower elevation, or else when the vehicle is provided with a running mode change-over switch for setting the running mode of the vehicle (e.g., a switch for setting sport running, fuel cost save running, and so forth) and the vehicle is controlled to run in response to a position of the control switch, control of the non-stage transmission cannot respond promptly to the running condition of the vehicle.
The present invention has been made to resolve the problems described above, and it is an object of the present invention to provide a controlling device for a non-stage transmission for a vehicle that can execute control of the non-stage transmission instantaneously and appropriately in response to a condition of an output power of an engine of the vehicle to improve the running performance.
Where a non-stage transmission is carried on a vehicle, the non-stage transmission is controlled such that the transmission gear ratio thereof may coincide with a target transmission gear ratio calculated in accordance with an engine parameter or the like during running of the vehicle, or the engine speed of the vehicle may coincide with a target engine speed calculated in accordance with an engine parameter or the like during running of the vehicle.
Such a controlling device for a non-stage transmission for a vehicle as described above is disclosed, for example, in Japanese Patent Laid-Open No. 62-273189.
In the case of the prior art described above, when the vehicle runs on an uneven road surface (e.g., a rough road), there is the possibility that the vehicle may suffer from hunting. The reason for the possibility of hunting will now be described.
FIG. 19 is a view illustrating a relationship between a vehicle which runs on an uneven road surface while maintaining an accelerator fixed and a transmission gear ratio of a non-stage transmission carried on the vehicle. It should be noted that, in FIG. 19, the degree of the unevenness of a road surface 905 is represented in an exaggerated manner in order to make the view easy to see.
In the figure, if a vehicle runs on an uneven road surface 905 while maintaining an accelerator thereof fixed, when the vehicle runs on an uphill road as denoted by reference numeral 901, the load to the engine is high. Accordingly, the transmission gear ratio of the non-stage transmission is set to a low side value (that is, a high transmission gear ratio side value). When the vehicle is running on a horizontal road as denoted by reference numeral 902, the engine load is low, and accordingly, the transmission gear ratio of the non-stage transmission is changed to a high side value (that is, a low transmission gear ratio side value). When the vehicle is running on a downhill road as denoted by reference numeral 903, the engine load is reduced further, and the transmission gear ratio is changed to a further higher side value.
FIG. 20 is a view showing a change in transmission gear ratio of a non-stage transmission when a vehicle runs on a level ground, an uneven road surface, a downhill road and an uphill road while maintaining a accelerator thereof fixed. In a table shown at the bottom of FIG. 20, a mark + indicates that the transmission gear ratio is being increased while another mark - indicates that the transmission gear ratio is being decreased, and 0 indicates that the transmission gear ratio does not vary.
As shown in FIG. 20, when a vehicle is running on level ground while an accelerator is maintained fixed, the transmission gear ratio is fixed, but when the vehicle runs on a downhill road or an uphill road, the transmission gear ratio is set from a low side value to a high side value or from a high side value to a low side value. When the vehicle runs on an uneven road surface (e.g., a rough road) while the accelerator is maintained fixed, the transmission gear ratio fluctuates between a low side value and a high side value as shown in the figure.
Generally, control of a non-stage transmission is executed for each predetermined sampling cycle, and depending upon a relationship between such sampling cycle and a cycle of the unevenness of a rough road, even if a controlling device for the vehicle judges, for example, that the vehicle is running on an uphill road and sets the transmission gear ratio to a low side value, the vehicle may actually begin to run on a downhill road. Then, if the controlling device judges that the vehicle is running on a downhill road and sets the transmission gear ratio to a high side value, the vehicle may actually begin to run on an uphill road. If such a situation as just described occurs repetitively, the vehicle will suffer from hunting, and there is a disadvantage in that a disagreeable feeling upon running on an uneven road surface is increased. The present invention resolves the problems discussed above.
A non-stage transmission which is carried on a vehicle typically changes the speed of a power of an internal combustion engine at a predetermined transmission gear ratio (ratio) to enable an efficient running of the internal combustion engine, by which improvements in fuel cost may be attained. Such a non-stage transmission is controlled so that, for example, the actual transmission gear ratio may coincide with a target transmission gear ratio which is calculated in accordance with a running condition of the vehicle. Such a controlling device for a non-stage transmission is disclosed, for example, in Japanese Patent Laid-Open No. 62-273189. A technique of fixing the transmission gear ratio of a non-stage transmission in a special condition such as reversing is disclosed, for example, in Japanese Patent Laid-Open No. 62-203830. The fixed transmission gear ratio is set to a comparatively high value on the low side so that starting of the vehicle and running of the same after then may be enabled.
The prior art just described has the following problems. In case the transmission gear ratio of a prior-art non-stage transmission is fixed, the transmission gear ratio is set to a comparatively high value on the low side as described above. Accordingly, when a running condition is entered after starting the vehicle, the engine speed likely becomes higher than that when the transmission gear ratio is not fixed (i.e., than when the transmission gear ratio is automatically controlled by a controlling device for the non-stage transmission). Accordingly, if running continues for a long period of time in this condition, there is the possibility that the engine may suffer from overheating. The present invention has been made to resolve the problems described above.
Some vehicles on which a non-stage transmission is carried have a device for automatically controlling the opening of a throttle valve so that an actual running velocity of the vehicle may coincide with a set running velocity to maintain a fixed velocity running, in order to reduce possible fatigue of a driver during running of the vehicle on an express-highway or the like. Such an automatic fixed velocity running device is disclosed, for example, in the official gazette of Japanese Patent Laid-Open No. 62-216836.
If, during automatic fixed velocity running, a vehicle begins to run on an uphill road having an excessively high inclination so that, consequently, the running condition of the vehicle changes, the load to the output side of an engine will be excessively high with only control of a throttle valve opening. Accordingly, in such an instance the automatic fixed velocity running control must necessarily be canceled. Thus, in conventional vehicles, transmission ratios of a non-stage transmission are set to rather high values in advance over all running conditions in order to widely follow a change in such running conditions.
The prior art described above has the following problems, which will now be discussed. Where transmission gear ratios of a non-stage transmission are set to rather high values compared to those for an ordinary case, the vehicle can execute automatic fixed velocity running against wide changes in a running condition of the vehicle due to running on an uphill road or the like as described above. However, when running the vehicle on level ground, the transmission gear ratio will then be excessively high. Consequently, the fuel cost will be high. In particular, since automatic fixed velocity running control and control of a non-stage transmission are executed independently of each other in a conventional vehicle, the fuel cost of the vehicle is sometimes high depending upon a running condition of the vehicle. Furthermore, since automatic fixed velocity running control in conventional vehicles is executed only by control of the opening of a throttle valve, the vehicle generally suffers from hunting.